Biology unit 3

Rhythms

Circadian Rhtyms: a daily rhythm

Biological Clock: timing mechanism in the body that helps to control various rhythms such as sleeping and waking-24 hour clock

hormones: chemical messnagers that are made in one part of the body and are carried in the blood to other parts which they affect, such as melatonin which changes the actions of the body so we feel sleepy.

Although bio-clock has its own built in rhythm it needs regualr exposure to day and night cycle to keep it in sync with the 24 hour clock - if we travel across the globe our bio-clock is not used to the change in 24 hour clock-jet lag

Plants have circadian rhythms aswell-flowers open durung the the day to attract insects for pollenation and they only produce nectar during the daytime and close during the night so pollen is protected form the wind,cold, damp and cold.

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Rhythms:Photoperiodism

Photoperiodism:the way in which living organisms respond to changes in day length.

winter- many plant species die in winter due to tough conditions but seeds survive

Spring-seeds sense lengtening days and begin geminate:the process in which a seed grows into a young plant

Some plants may not die in winter but respond ot lengthening days by growing faster. In Autum as days get shorter plants stop growing and prepare for tough winter.

Flowering also controlled by length of dark and lihgt in 24 hour clock

Flowers when:

Iris- more than 12 hours of light

Poinsettia:more than 14 hours of dark

Spiaich:more tahn 14 hours of light

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Plant Defenses

Pests:animals such as insects or lareg herbivores that eat and damage crops

Louis Pasteur:French Bio-chemist showed that micro-organisms were responsible for some diseases and food going off and developed the method of pasteuristaion.

Aspectic techniques:any method to ensure that living micro-organisms do not come into contact with something eg. pasturistaion

Pasteurisation:when foods such as milk are heated briefly to kiol the bacteria in them

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Vaccines

Edward Jenner discovered the first vaccine for smallpox- found that milkmaids caught a cowpox did not get small pox.Jenner took a cow pox blister and rubbed it on the skin of 8 year old Jaes Phipps-jame sdid not get small pox-cowpox vaccine had made him immune to smallpox.

Vaccine:a substance containing dead or weakened pathogens or parts of them,introduced into the body to make a person immune to that pathogen

Antigens:a protein that white blood cells recognise as foreign

Antibodies:a protein produced by lymphocytes.Ir attaches to a specific antigen on a micro-organism and helps to neutralise or destroy it.

lyphocytes: a type of white blood cell that produces anitbodies

memory lymphocytes:a lymphcyte that remains in the blood long after an infection or vaccination

infection:the entry of pathogens into the body;an illness caused by a pathogen

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Vaccines

immune response: the response of the body to attack by invading pathogens

immunisation:making someone immune

1.weakend pathogen injected intotthe body , it has antigens on the surface.

2.a lymphocyte with an antibody that perfectly fits the antigen is activated.

4.some of the lymphocytes secrete large amounts of antibodies which stick to the patogens and destroyt them.Others remain in the blood as memory lymphocytes ready to respond immediatley if another infection occurs.

Advantages of Immunistaion:

child can become immune without suffering from disease

chances of long lasting harm are much less than if the person actually catches the disease

If enough children are vaccinated - makes it rare for even unvaccinated children to get it.

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Risks of Immunisation and Antibodies

quite comman for person to get swelling or redness around the are of injection

some children may get a mild form of the disease being vaccinated against.

ver raley do children suffer an allergic reaction to the vaccine.

Antibodies

Primary respones:the way in which the immune system responds on the first occasion that a particular pathogen enters the body-takes a while for lymphcytes to multiply and secrete antibodies.

Secondary Response:the way in which the immune system responds on the second occasion that a particular pathogen enters the body-immediatley make right antibodies.More likely that lymphocytes will be able to produce antibodies to destroy the pahogen even before they have a chance to increase in number and make the person ill.

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Monoclonal Antibodies

Monoclonal Antibodies:many identical antibodies

Clones:a cell or organism that is genetically identical to the parent cell or organism

B Lymphocyte: a type of lymphocyte that produces antibodies and cannot divide anymore

Hybridoma: a cell made by fusing a lymphocyte with a cancer cell

Process

1.a particular antigen is injected into a mouse.the mouse produces lymphocytes that make antibodies against the antigen.

Myeloma(cancer cells) grown in cutured medium.

2.B Lymphocyte from mouse and cancer cell fused.

3.The hybridoma cell can both divide and make antibodies against the antigen.These are monoclonal antibodies

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Using monoclonal antibodies

Preganacy testing kits: used to detect hormone HGH found in the urine of pregnant women. If there is any HGH is present ,it binds with monoclonal antibodies on the stick and cause a colour change .

Also can be made slightly radioactive: radioactive monoclonal antibodies injected into body and it binds tot he substance found in the mebranes of platelets and cancer cells and radiologists able to detect where the antibodies are -allowing them to treat the cancer or blood clots.However it is difficult to make sure that only the target areas are affected.

Drugs can be attachted to monoclonal antibodies to deliver drugs only to the cells that need to be destroyed-less drug is wasted and there is a decreased risk of harming healthy cells.

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The Kidneys

Metabolic reactions:chemical reactions happening inside the body

Urea:a waste product produced in the liver fomr excess amino acids

Renal Arteries: an artery that delivers blood to the kidneys

Renal Veins: a vein that carries blood away from the kidneys

urine:a fluid produced by the kidneys,containing urea and other waste products dissoloved in water

ureters:one of the tubes that carry urine from the kidneys to the bladder

bladder:the organ where urine is stored

urethra:the tube that carries urine from the bladder to the outside of the body

kidneys:one of the organs in the abdomen that removes urea and extra water from the blood by producing urine

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Kidney Failure

Treating Kidney Failure

Can't put any kidney into a persons body.Kidney cells have antigens on them that the immune system may attack as they detect it as foreign-rejected. Antigens on the organ must be very similar to those on a patients cells.

Long time to find a replacement kidney.Sometimes a family member can donate a kidney as they may have similar antigens

Need life long medication to prevent rejection.The medication effects the body's response to infection-may catch disease like colds more easily

Kidney Transplant:taking a healthy kidney form one person and putting it into the body of another person

Kidney Dialysis:process used to clean the blood of people with kidney failure,using membranes to filter out waste products.

Machines are expensive and patients will be connected for long periods of time

Rejected:to refuse or get rid of ,such as when the body reacts to the foreign tissue of a transplant and kills it.

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Inside the kidneys

1.Blood flows along th renal artery and into the network of capillaries called the glomerulus,which runs inside the Bowman's capsule of the nephron

2.The capsule has tiny holes that lest really small molecules such as water urea and glucose through the nephron.Big molecules such as proteins, blood cells stay in the blood this is known as filtration.

3.The fluid flows along inside the nephron.Some substances are absorbed back through the walls of the nephron into the blood.Only useful substances that the body needs return to the blood such as glucose - selective reabsorbtion

4.Water is also reaborbed depeneding on how much the body needs-osmoreguation.

5. At the end of the nephron the reamainig fluid flows into the ureter. The fulid contains excess water that the body no longer needs + urea and other waste sunsatnces-urine.

Bowman's capsule:the part of the kidney tubule where blood is filtered

Glomerulus:network of capillaries

Nephron:a kidney tubule

collecting duct:thepart of th ekidney tubue where water is reaborbed

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Inside the kidneys

convoluted tubules:a part of the kidney tubule where glucose and other useful substances are resorbed into the blood.

loop of henle:part of the kidney nephron that loops down and then sharply upwards,helps with osmoregulation.

Filtration:separting large molecules form the smaller ones using a partially permeable membrane as in the Bowman's capsule.

Selective Reabsorption:taking back useful substances into the blood,form fluids inside the nephron.

Osmoregulation:the maintenance of an organisms water content and dissolved salt concentration, a function performed by the kidneys.

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Controlling water content

Kidneys help to control the water content of the blood. Pituitary gland secretes ADH (Antidiuretic hormone)

Not Enough Water

The brain senses there is not enough watre in the blood.

the piturity gland secretes more ADH.

The ADH causes the kidneys to reabsorb more water.

A small volume of concentrated urine is produced.

To much Water

the brain senses there is too to much water in the blood.

The pituitary secretes less ADH

This makes the kidneys reabsorb less water.

A lareg volume of dilute urine is produced.

Negative Feedback:a control mechanism in which a change in factor causes an action that reverses the change.

The Menstrual Cycle

Menstruation:the breakdown and loss of the lining of the uterus, at the start of the menstrual cycle.

Oestrogen:a hormone produced by the ovaries important in the menstrual cycle.

Progesterone:a hormone produced by the ovaries and placenta ,which helps to maintain the thick lining of the uterus.

1. Menstruation takes place between the 4 and 7 days in the first week of the cycle.

2.During the second week the lining of the uterus gradually builds up.

3.Ovulation usually takes place around day 14.

4.Days 14-16 are when fertilizations most likely to take place.

5.The lining of the uterus continues to build up throughout weeks 3 and 4.

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Menstrual Cycle

The menstrual cycle stops if an egg id fertilised.When this happens the thickened lining of the uterus stays in place so that the embryo can embed into it and begin to develop-missing a normal menstrual period is the first clue that a woman may be pregnant.

Hormones and the Menstrual Cycle

FSH:

LH:

Piturity gland:

Follicle:

Corpus Luteum:

FSH

The hormone FSH is secreted by the pituitary gland. FSH makes two things happen:

it causes an egg to mature in an ovary

it stimulates the ovaries to release the hormone oestrogen

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Menstrual Cycle and Hormones

Oestrogen

The hormone oestrogen is secreted by the ovaries. Oestrogen makes two things happen:

it stops FSH being produced - so that only one egg matures in a cycle

it stimulates the pituitary gland to release the hormone LH

Controls the releasal of hormones.

LH

The hormone LH causes the mature egg to be released from the ovary.

Progesterone:

secreted by the follicle after it releases the egg and becomes a corpus lutem.

If fertilisation occurs the corpus luteum will continue to secrete progesterone so that high levels of the hormone remain.

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Menstrual Cycle

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Menstrual Cycle

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Fertilisation

Fertilisation:the joining together of two nuclei

Humans reproduce through sexual reproduction. This involves two parents. Sexual reproduction produces offspring that are unique individuals. Half of their genes come from each parent.

Diploid:cell that has 2 sets of chromosomes

Haploid:containing a single set of chromsomes such as gametes.

Gametes

Gametes are the sex cells:

Eggs are female gametes

Sperm are male gametes

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Fertilisation

Gametes have adaptations to increase the chances of fertilisation and successful development of an embryo. For example, sperm cells are produced in large numbers to increase the chance of fertilisation. Sperm cells have these adaptations:

A tail to move them towards an egg cell

Many mitochondria to provide energy

An acrosome (part of the tip of the head) that releases enzymes to digest the egg membrane

Fertilisation

In sexual reproduction, a male gamete and a female gamete join together. This is fertilisation.

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Fertilisation

Process of fertilisation Gametes are produced by a type of cell division called meiosis. A gamete is haploid – it contains just one of the chromosomes from each pair, and half the genetic information of a body cell. Fertilisation leads to genetic variation because: Two gametes combine to form a diploid zygote Genes on the chromosomes combine to control the characteristics of the zygote.

IVF: (in vitro fertilisation) some of woman's egg are taken and are fertillised in a dish with partners sperm. One or 2 of the embryos are inserted into the females uterus to develop.

Often IVF babies are born earlier-may cause birth problems or development later

Egg Donation: egg taken from another woman who has been given hormones and the IVF is carried out using her eggs and the selected patners sperm.

Few women who donate eggs react badly tot he hormones

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Infertility Treatment

Surrogate mothers: woman unable to grow an embryo in her uterus then her patners sperm is used to fertilise one of her eggs or a donated eggs. The fertilised egg is then inserted into another woman uterus-surrogate mother who gives birth to the baby.

Handing over the baby may be a problem as she may become attached due to a strong bond forming and she may not want to give it up.

Homrones: chemical messanger that are made in one part of the body and are carried away in the blood to other parts to have an effect

extra hormones may help a woman's ovaries to produce eggs.

Increases the chance of having more then 1 baby

these babies are usually born earlier and may have increased risk of illness and disease after birth and then later in life

In vitro fertilisation:fertilising and eggs by placing it in a sterile container with sperm

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Sex Determination

A Punnett square for sex determination :Because men are "heterozygotes" it is their sperm that determines whether the woman gives birth to a son or daughter. Men determine the sex of their children.

Sex Chromosomes:

Phenotype:the characteristics of an organism

Genotype:the alleles of a particular gene possessed by an organism

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Sex Linked Inheritance

Chromosomes come in matching pairs. Same genes but differnt alleles-altenative forms of the gene.

X chromosomes are much bigger than the Y chromosome so there are many more genes of the 'X' -this means males will only have one copy of most genes found on the 'X'

Haemophilia:a disorder of blood clotting caused by a recessive allele on the X chromosome and is a sex linked gentic disoredr:a condition caused by an allele of a gene carried either by the X or Y chromosome.

Normal Allele: 'H' allows for the blood to clot properly.

The recessive allele:(version of the gene that will only have an effectif the other allel id recessive) 'h' prevents normal clotting

XHXH: FEMALE NORMAL BLOOD CLOTTING

XHXh:FEMALE CARRIER BUT NORMAL BLOOD CLOTTING

XhXh: FOETUS DOES NOT USUALLY DEVELOP

XHY:male normal blood cltting

XhY: male haeophilia

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Sex Linked Inheritance

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Sex Linked Inheritance and Courtship and Parenting

MUST SHOW CHROMOSOMES

1 in 4 chance of having a boy with haemophilia (1:3 or 25%)

Red-Green Colour Blindness:a sex linked genetic disorder in humans where the affected individual cannot distinguish the colours red and green , more common in men than women also found on the X chromosome

Courtship and Parenting

Behaviuor: the ways in which anials resond to internal and external stimuli.

Choosing a mate

Reproductive quality:the ability of an individual to produce healthy offspring

Courtship Behavior :actions that help male and female organisms to attract to one another and to maintain a bond between them

male ofetn displays to the females that he is a high quality chose - eg. birds brightly coloured and have large feathers.

Female is often well camofluaged ot be able to evade predators and care for young

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Courtship and Parenting

Mating Strategies

• sexual reproduction requires the finding and selection of a suitable mate, and can involve courting behaviour

• some animals mate for life(swans), others select several different mates during the mating season(deer),a amte over a breeding season(robins)

Caring for young

Mammals:feed their young and teach them how to find food and avoid predators

Birds: keep their young in theri nest,sitting on them to keep them warm and briging them food until they are able to fly.

Increase chance of survival of offspring that will carry on parents genes into futher generations

• parental care is a successful evolutionary strategy; although it involves risk to the parents, it can increase the chances of survival of the parental genes.

Evolutionary Strategy: Any process that effects how a species change over time and spreads- parental care ensures that plenty of offsrpign survie-the more offspring there are the more likley adaptions willl take place so the species can evolve and spread.

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Innate Behavior and Imprinting

Innate Behavior:Inborn, behavior that does not need to be learnt and is automatic, not thought about eg.baby's startle reflex or a dragonfly nymph

Increase chances of survival and is controlled by genes.Animals with useful innate behavior more likely to survive reproduce and pass on genes

Tinbergen and the herring gulls:founded ethology (study of animal behavior) and noticed that herring gull chicks pecked ta the beaks of parents to make them regurgitate food.Adults beak had a red spot.used various cardboard cut outs of herring gulls but with different coloured dots and testes the effectiveness.

Imprinting:the process in which young animals bond with or become attached to animal or moving objects they see immediately after birth or hatching

Lorenz and imprinting on geese:new born geese and ducklings llearn to stay close to mother-advantage as it offers protection and allows for young birds to learn *** to find food.

Lorenz found that when the birds hatched in the incubator they became attache to whatever they saw first

Learning: a relative permanent change in behavior due to previous experience

very short window of learning but it lasts well into adulthood

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learned Behavior

Habituation:a process in which an animal learns not to respond to repeated stimulus.

adaption to envirnoment eg.sea hare is repeatedly touched it no longer thinks there is danger and does not withdraw its gills for protection aginst predators

Classical Conditioning: a proces in which a reflex response is associacted with a new stimulus.

Pavolov

starts with innate reflex such as salivation to a natural stimulus such as food but is now asscoiated with new stimulas such as a bell

Operant Conditioning: a process in which an animal changes behvaior due to unpleanst consequences or rewards

Skinner's box-rat in box shocks and presentation of a reward

discovered by accident by then begins to associate begaviour with pleasnt/unpleasant experience

Training animals:changing an animals behaviour by givign them a reward or punisment

sniffer dogs:rewarded for locating the right smell - dog learns to look for particular smell

Police horses:repeatedly exposed to loud noises and smoke learns not to be afraid of it

Dolphins:loctae mines

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Animal Communication

Communicate: the exchange of information between organism

Visual Signs: body language(body positions and gestures that give the observers information about the way an animal is feeling (eg.courtship behaviours)

Chemical Substances: production of pheromones(a substance produced by an organism that diffuses into the air and causes response in other animals.

Social Behvaiour: the way in which a group of organisms intercat with each other

Diane Fossey:American zoologist;studied social behavior in mountain gorillas in Rwanda-by imitating behaviour she was accepted into the group/gorillas also have complex family relationships and were not violent/able to work out meaning of calls and was the first to understand how their society worked

Jane Goodall:British researcher;chimpanzees in Tanzania-recorded and observed behaviour/first person to learn the chimps use tools to help them obtain food and that they hunt together.

Their work has allowed us to understand the complex societies and uses of communication in chimps and gorillas and has given us insight into human behaviour

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Plant Communication

Communicating with animals:

Flowers have evolved brightly coloured chemicals in the petals that attract insects to them.

Produce chemical scents that spread out into the air-insects find the flower by moving towars the highest concentration fo scent.

Some plants also produce brightly coloured fruit that animals such as birds recoginise as being ripe .Inside are seeds which are consumed by animals and then dispersed in animal's waste .

plants often produce chemicals that can harm insects to be able to have protection agianst being eaten

all of this is need for the pollination of flowers and the dispersal of the seeds.

Communicating wit other plants:

some acacia tress produce a chemical that is distasteful and poisonous to deter herbivores form eating them-takes a lot of energy so only done when under attack.

Leaves produce ethene which diffuses to nearby acacia trees who pick up the warning of an attack and start to produce chemical evenbefore the pests can eat them.

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Co-Evolution of Plants and Animals

Evolution: the development of new species over time through the process of natural selection

Co-evolution:the way in which 2 different species affect each other's evolution

Pollination:transfer of pollen from one flower to another enabling fertilization

plant chemical defense:some plants have evolved to defend themselves against attack form herbivore by producing toxic compounds;some insects have co-evolved to allow the insects to eat the plant

Examples:

Pollination of flower by insect- insects recognise bright colours and scents this is to their advantage as they are bale to find food. Beneficial for plant as it means they are more likely to be pollinated

so as one species changes over time the individuals of the other species that are best suited to those changes are more likely to adapt.

Few plant species in Australia make poison in their leaves which the grey kangaroo are able to eat- in places where there are fewer kangaroos the plants don't waste energy making poison.

**** Habilis:discovered by the Leakey/2.4-1.4 million years ago/wlaked upright/quite short with long arms/ brains 500-600cm/tools found

**** erectus:discovered by the Leakeys/1.8-0.5 million years ago/tall/1.79 m/strongy built/850 brain/tools found

**** sapiens: 195000 years ago to present day/ 1500 cm brain

Stone Tools

cannot be dated directly to exact period but there age can be determined by the layers of rock and sediment found with them - so we assume the tool is the same age as the sediment.

Very simple tools that would have helped with cutting and skinning animals but in recent rock they are more sophisticated

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Human Migration

Climate change and Human Behaviour:

**** sapiens first evoled form Africa

Around 60 000 years ago there was an Ice age- very cold periods called glacials and warmer intergalcials- alot of water was locked up in ice and sea levels were much lower making it easeir to cross form Afica to Yemen.

People would move in oredr to hunt and gather food.

Intergalcial period there was a spread across Europe and Asia and they adapted tools,clothing,homes, and euipment to suit their new environments.

25 000 years ago another cold period produced land bridges between Siberia nd North America allowing humans to spread.

11000 years ago the climate became more stable and people began to settle down even starting to grow crops.

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Mitochondria DNA

Mitochondria:the site where cellular respiration takes place, where glucose is broken down using oxygen to release energy which is needed for reactions in the cell

Nuclear DNA:the DNA found in the nucleus of a cell

Mitochondria DNA:The DNA found inside the mitochondria, which is passed by mother to all the offspring without any mixing;sons do not pass down their mothers mtDNA to theri children

African Eve:a woman who live in Africa between 130 000- 200 000 years ago and passed on mt DNA to all humans living today.

does not mean she was the only female living there- it jsut shows the unbroken female to female heritage line all the way form her generation

Evidence also shows how we are all very closley related which suggests how humans spread out of Africa

All the mitochondria come from the cytoplasm in the the egg cell(needed for meiosis) so the DNA only comes from the mother.

mt DNA mutates 100-1000 x faster than nuclear DNA allowing for greater adaptions-meaning that over 50 000 years many more mutations have happened to mt DNA.

The fact that mitochondrial DNA is maternally inherited enables researchers to trace maternal lineage far back in time.

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Mitochondria DNA

Advantages and Disadvantages of mt DNA

Each cell only has one nucleusBut each cell contains thousands of mitochondria which contain numerous DNA molecules.

Nuclear DNA can be very easily degraded or contaminated by environmental conditionsas wheremtDNA does not appear to be negatively impacted .Therefore aged samples of bones may easily yield mtDNA. Badly burned materials, and skeletonized bones can easily have mtDNA present.

The only disadvantages are that it is not as precise as nuclear DNA, and siblings will have the same mtDNA.

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Biotechnology

Biotechnology:the alternation of natural biomolecules using science and engineering in order to provide goods and services

Biomoleules: a substance made by a living organism

Fermenters:a container in which microorganisms are cultured to produce useful substances on a large scale-the product is collected from the solution in which the microorganisms have grown.

inside the fermenter microrganims are provided with exactly the right conditions to encourage them to grow and produce the substance required.eg. the cultivation of the fungus Penicillin.

Before the microorganism is placed inside the fermenter it si sterilized(to destroy bacteria,viruses,mould and pests) using high pressure steam to make sure that nothing else grows instead.Everything added to the fermenter is sterilised.

This is known as aseptic precautions: any method used to ensure that living microorganisms do not come into contact with somehting.

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Conditions inside a fermenter

Optimal conditions are used to make the most amount of product in the shortest amount of time.

Nutrient: a substance required by an organism for growth or energy-carbs and nitrogen such as ammonia ions and sugar.

Optimum Temperature:Temperature at which an enzyme's rate of reaction is fastest or at which the population of microorganisms grows mist rapidly

Optimum pH: pH at which an enzyme's rate of reaction is greatest, or at which a population of microorganisms grows most rapidly

Agitation:mixing the contents of a liquid eg stirring

Oxygen:bubbling sterile air so aerobic respiration can take place.

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Microorganisms for food

Mycoprotein:a protein rich food made from fungi

Fusraium:a type of fungus thatis grown in fermenters to produce mycoprotein as a food sourceand is made a tiny fibres calle hyphae-no stirrer in th fermenter because it would break and tangle the fibres

1. the fibres are collected and heated to remove the bitter tasting substance. they are dried and pressed to from fibrous substance.

Advantages of Microorgansims as Food

grow much faster than crops or animals.

easy to handle and manipulate.

Grown in fermenters so do not take up space.

can be grown in any part of the world and in any weather.

can be grown using waste materials for other processes eg. Fusraium is grown on waste material produced whne flour is made form wheat grains

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Mycoprotein as a Food Source

mycoprotein contains no saturated fat but meat does .

high fibre content slows down the rate at which glucose is abosorbed into the blood and prevents it bllod glucose fro riseing rapidly after a meal.

Means insulin is not secreted so quickly or in large amounts which decreases the risk of developing type 2 diabetes.

high protein/carb and fibre content needed for balanced diet.

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Enzyme Technology

Enzymes: a protein produced by living organism that act as a biological catalyst to speed up the rate of reaction

Enzymes for Sweets: Invertase (aslo known as sucrase catalyses the conversion of sucrose into glucose and fructose) is produced by cultivating Saccharomyces cerevisae (a species if yeast used in bio technology). Sucrose found in sugar cane and beet and is converted into fructose and glucose.

fructose+glucose is sweeter than sucrose and is used as an alternative sweetener/sweet foods and soft centred sweets.

Enzymes Iin washing powder

proteases breaks down proteins such as haemoglobin in blood stains and lipases to break down fats such as grease.

Enzymes in cheese making:

chymosin protein disgesting enzyme used to make cheese that can be produced by genetically modified bacteria .It affects the milk by separating it in curds and liquid whey.

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Genetically modified Organisms

1980's found a way of making chymosin from bacteria-made from genetically modified yeast and allows for vegetarians to eat it.

Genetic Modification:

DNA form human cell is cut into piecess using a restriction enzyme(an enzyme that cuts DNA molecules into pieces) leaving sticky ends.

Bacteria cells contain plasmids( ).Cut up with restriction enzymes leaving sticky ends(a length of DNA with only one strand , that will easily join with other pieces ) that match up with the unpaired bases.

The pieces of the DNA containing characteristic gene are mixed with the plasmids and the sticky bases pair up. DNA ligase(an enzyme that joins 2 DNA molecules together) is added linking it into a continuous circle.

The recombinant plasmids are inserted into the bacteria and are grown in huge fermenters where they make eg. insulin.

Transgenic:the new gene has come from different organism and if it is from a different species it is known as transgenic

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Global Food Security

Global food security crisis:the ability to produce enough food in the future to feed everyone in the world

conventional breeding:producing offspring using the natural technique of cross breeding .eg producing high yielding wheat variety -one high yielding variety is crossed with another . The resulting seeds are sown and grown. Plants producing the most grain are selected and are bred together-repeated for at least 20 generations eventually producing a high yielding variety which is named and sold

Pest management strategies

Integrated pest management strategies:reducing the populations of insects and other pests by coordinated method of different pest control strategies.Example:Raspberry crops.

Conventional breeding produced varieties that are resistant to aphids.

The environment where the raspberries are grown are grown to be more attractive to the natural predators of the raspberry beetle.

Chemicals produced by rasperyy plants put into traps to lure beetle which are killed in soap solution

Pesticides are sprayed but only when traps show large numbers.

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Biofuels

Bio fuels:a fuel made from plants or microorganisms.

Renewable:something that can be made without diminishing the resources used to make it eg.bio fuels.

Advantages:

renewable

carbon neutral- carbon released into the air is balanced by the amount of carbon dioxide they remove through photosynthesis.

Disadvantages

takes up land that can be used to grow crops.

may be expensive

difficult ot change everything.

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Genetically modified Future

GM crop seeds are produced in developed countries are more expensive than normal seeds.Developing countries may borrow money to buys seeds to have better crops.However it may lead to decreased production of crops as the seeds are not adapted to the soil and so the farmers have less money and food.

GM is being used to make crops reistant to tinfectio, viruses ,weeds and pests in developed and developing countries allowing for more crops and more food.

Production of GM plants:

transgenic:plant containing genes that have been taken from another species

Bacillus thuringiensis:a bacterium that produces a substance that is toxic to insects that destroy crop plants.some crop plants have been genetically modified with this gene

Agrobacterium tumefaciens: a bacterium used as a vector in genetic modification

vector:a go between that is used in genetic modification to transfer genes from one cell to another.

Bt toxin:a poison produced by the bacterium which is eaten by insects .helps to reduce crop damage.

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Making GM plants

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Advantages and Disadvantages of Bt crops

Advantages:

less insecticide used.

reduced damage on environment

higher yields should be produced due to less loss due to pests.

disadvantage:

could kill other harmless insects eg. butterflies.

Bt gene may spread to closely related wide plants which would make them resistant to bugs and then would become overpopulated.

insect populations may evolve to become resistant to the Bt( plant-co evolution).